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October 10, 2007

TOTD #11: Setup Mongrel cluster for JRuby-on-Rails applications on Unix

Filed under: web2.0 — arungupta @ 11:00 pm

This TOTD explains the steps to setup a Mongrel cluster for JRuby-on-Rails applications on a Unix flavor operating system. These instructions do NOT work on Windows. A similar post for Windows is cooking and will be posted when ready.

  1. Download JRuby 1.0.1 and unzip the bundle (say JRUBY_HOME).

    1. For convenience, include JRUBY_HOME/bin to your PATH.

  2. Install the required RubyGems

    1. Install Rails as shown below:

      jruby -S gem install rails --version 1.2.3 --include-dependencies --no-ri --no-rdoc
      Bulk updating Gem source index for:
      Successfully installed rails-1.2.3
      Successfully installed activesupport-1.4.2
      Successfully installed activerecord-1.15.3
      Successfully installed actionpack-1.13.3
      Successfully installed actionmailer-1.3.3
      Successfully installed actionwebservice-1.2.3

    2. Before installing Mongrel, install the pre-requisite Gems as shown below (see discussion here):

      jruby -S gem install gem_plugin --no-ri --no-rdoc
      Successfully installed gem_plugin-0.2.2

      and another one:

      jruby -S gem install cgi_multipart_eof_fix --no-ri --no-rdoc
      Successfully installed cgi_multipart_eof_fix-2.3

    3. Mongrel cannot be installed as a gem on JRuby yet. So download Mongrel gem and install it as shown below:

      jruby -S gem install mongrel-1.0.1-jruby.gem --no-ri --no-rdoc
      Successfully installed mongrel, version 1.0.1

      Make sure to invoke the command from the directory where the gem is downloaded.

    4. Install Mongrel cluster. mongrel_cluster does not work with JRuby and so instead mongrel_jcluster needs to be installed as shown below:

      jruby -S gem install mongrel_jcluster --include-dependencies --no-ri --no-rdoc
      Successfully installed mongrel_jcluster-0.0.1

      As mentioned here, mongrel_jcluster is still quite experimental and not guaranteed to work in any way but it worked for this post :)

  3. Create a template application say in JRUBY_HOME/samples as shown below:

    /home/arung/testbed/jruby-1.0.1/samples/rails 1954 $ ../../bin/jruby -S rails hello
          create  app/controllers
          create  app/helpers
          create  app/models
          create  log/production.log
          create  log/development.log
          create  log/test.log

  4. Start Mongrel as shown below:

    cd hello
    /home/arung/testbed/jruby-1.0.1/samples/rails/hello $ ../../../bin/jruby script/server
    => Booting Mongrel (use 'script/server webrick' to force WEBrick)
    => Rails application starting on
    => Call with -d to detach
    => Ctrl-C to shutdown server
    ** Ruby version is not up-to-date; loading cgi_multipart_eof_fix
    ** Starting Mongrel listening at
    ** Starting Rails with development environment...
    ** Rails loaded.
    ** Loading any Rails specific GemPlugins
    ** Signals ready.  TERM => stop.  USR2 => restart.  INT => stop (no restart).
    ** Rails signals registered.  HUP => reload (without restart).  It might not work well.
    ** Mongrel available at
    ** Use CTRL-C to stop.

    The application is now available at http://localhost:3000. Hit Ctrl-C to stop Mongrel as shown below:

    ^C** INT signal received.
    `require': Mongrel::StopServer (Mongrel::StopServer)
            from /home/arung/testbed/jruby-1.0.1/lib/ruby/gems/1.8/gems/rails-1.2.3/lib/commands/server.rb:39
            from /home/arung/testbed/jruby-1.0.1/lib/ruby/site_ruby/1.8/rubygems/custom_require.rb:27:in
            from /home/arung/testbed/jruby-1.0.1/lib/ruby/site_ruby/1.8/rubygems/custom_require.rb:27:in
            from :1

  5. Configure and Start Mongrel cluster

    1. Configure Mongrel cluster as shown below:

      /home/arung/testbed/jruby-1.0.1/samples/rails/hello $ ../../../bin/jruby -S mongrel_rails jcluster::configure -p 8000 -N 2
      Writing configuration file to config/mongrel_cluster.yml.

      This starts a cluster of 2 Mongrels (identified by -N 2) assigning ports in the ascending order starting at 8000 (identified by -p 8000).

    2. Start Mongrel cluster as shown below:

      /home/arung/testbed/jruby-1.0.1/samples/rails/hello $ ../../../bin/jruby -S mongrel_rails jcluster::start
      ** Ruby version is not up-to-date; loading cgi_multipart_eof_fix
      Starting JRuby server...
      Starting 2 Mongrel servers...

  6. Now your application is available on http://localhost:8000 and http://localhost:8001. All the logs (for all the instances) are available in log/development.log.

  7. The cluster can be stopped as shown below:

    /home/arung/testbed/jruby-1.0.1/samples/rails/hello $ ../../../bin/jruby -S mongrel_rails jcluster::stop
    ** Ruby version is not up-to-date; loading cgi_multipart_eof_fix
    Stopping 2 Mongrel servers...

A follow up post will show how to front-end this cluster of Mongrels with a light-weight HTTP server.

An alternative to this behemoth configuration is to create a Web ARchive (WAR) of your JRuby-on-Rails application and deploy on GlassFish. A complete screencast of how this can be achieved using NetBeans IDE is shown here. A comprehensive list of JRuby on GlassFish documentation is available here.

Technorati: totd rubyonrails jruby mongrel unix jrubyonglassfish glassfish netbeans ruby

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Related posts:
  1. TOTD #13: Setup Mongrel for JRuby-on-Rails applications on Windows
  2. TOTD #14: How to generate JRuby-on-Rails Controller on Windows (#9893)
  3. TOTD #24: Getting Started with Rails 2.0.x in JRuby 1.0.3 and JRuby 1.1RC1
  4. JRuby 1.0.3 + Rails 2.0 Hello World – Additional Steps Required
  5. TOTD #79: Getting Started with Sinatra applications on JRuby and GlassFish Gem


  1. [Trackback] In a previous entry, I posted instructions on how to setup Mongrel cluster for JRuby-on-Rails applications on Unix-based systems. The instructions specified there do not work on Windows-based systems because of the following reasons: JRuby 1.0.1 + (def…

    Comment by Arun Gupta's Blog — October 12, 2007 @ 9:38 am

  2. Nice write-up! I think there’s a small error in item 5: you need the -S option when you run mongrel_rails with jruby.

    Also, the server only starts on port 8000.

    Comment by Kjetil — November 23, 2007 @ 4:27 am

  3. Thanks for the catch, fixed the typo!

    When the Cluster was configured, then I could see exact same page hosted at port 8000 and 8001. Can you explain your second comment ?

    Comment by Arun Gupta — November 23, 2007 @ 5:36 am

  4. I’ve followed above configurations for jruby mongrel_cluster but I’m getting the below error

    jruby -S mongrel_rails jcluster::start
    Starting JRuby server…
    Starting 2 Mongrel servers…
    sh: jrubycli: command not found
    mongrel_rails start -e development -p 8000 -P log/

    sh: jrubycli: command not found
    mongrel_rails start -e development -p 8001 -P log/

    Comment by sagi — September 18, 2009 @ 9:45 pm

  5. sagi, I’ve not tried the configuration for sometime now. Please ask your question to .


    Comment by Arun Gupta — September 22, 2009 @ 10:09 pm

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